TUESDAY, Oct. 1 (HealthDay News) -- Exercising during your leisure time could help prevent high blood pressure, but being physically active at work doesn't seem to provide the same benefit, according to a new review.

Researchers analyzed the findings of 13 studies that examined the effects of physical activity on blood pressure. The studies included a total of nearly 137,000 people in the United States, Europe and East Asia who initially had healthy blood pressure. During follow-up periods ranging from two to 45 years, more than 15,600 of the participants developed high blood pressure.

Compared to people who exercised less than one hour a week during their leisure time, the risk of developing high blood pressure was 11 percent lower among those who exercised one to three hours per week, and 19 percent lower among those who did more than four hours of recreational exercise a week, according to the study published Sept. 30 in the journal Hypertension.

The results suggest that the more leisure-time exercise you do, the lower your risk of developing high blood pressure.

However, the researchers did not find a solid link between physical activity at work and high blood pressure risk. Physical activity on the job, such as farm or industrial work, can involve heavy lifting, prolonged standing and repetitive tasks.

Exercise guidelines don't distinguish between physical activity at work or during leisure time, but "given the new findings, perhaps they should," study co-author Dr. Bo Xi, a lecturer at the Shandong University School of Public Health in Jinan, China, said in a journal news release.

Recreational exercise may help reduce the risk of high blood pressure by preventing weight gain, improving poor insulin sensitivity or reducing the blood vessels' resistance to blood flow, the researchers suggested.

But they noted that their findings don't show that leisure-time exercise actually prevents high blood pressure. People who exercise for fun may just have healthier lifestyles, Xi explained.

About 78 million U.S. adults have high blood pressure, which is a risk factor for heart and kidney disease.